Animals often engage in intraspecific conflict to increase their access to resources, and for social species, to improve their rank within the society. Differences in intrinsic fighting ability contribute to differences in contest success. However, prior experience can also contribute to the outcome of conspecific competition. Success in a previous encounter can increase aggressiveness and raises an individual’s probability of winning future contests, a phenomenon known as the winner effect. Likewise, a prior loss can promote docility and reduce the probability of future wins, known as the loser effect. While the physiological mechanisms underlying these effects are largely unknown, research on vertebrates and invertebrates supports that winner and loser effects are also influential in the formation of dominance hierarchies.
Theoretical and empirical research suggests that a winner effect can only exist in the presence of a loser effect. However, recent evidence suggests that this is not always the case. This finding prompted the present study, which explores the presence of a winner effect in virgin honey bee queens (Apis mellifera). Following the death or departure of the previous queen in a swarm, young virgin queens engage in fatal contests for the opportunity to become the new reproductive individual in the colony. To test for winner effects, I reared virgin queens and staged duels between pairs in Petri dishes. The duels occurred between either two age-matched queens or between a younger and older queen. Following this, the winner of the contest was pitted against another age-matched queen with no fighting experience.
The results indicated that prior winners did not experience an increase in winning probability, and thus a winner effect was not detected. This may be attributed to the lethal nature of the contests, which can promote high-risk injury and reduce the importance of prior experience. The study also led to observation of novel behaviors including proboscis pairing between opponents. Finally, this study provides novel insight into the behavioral displays (antagonistic and non-antagonistic) produced by virgin queens whose outcomes determine the genetic composition of their entire colony.